Thermal energy storage and cooling system with secondary refrigerant isolation

ABSTRACT

Disclosed are a method and device for a refrigerant-based thermal storage system wherein a condensing unit and an ice-tank heat exchanger can be isolated through a second heat exchanger. The disclosed embodiments provide a refrigerant-based ice storage system with increased reliability, lower cost components, and reduced power consumption compared to non-isolated systems.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of DivisionalApplication No. 12/879,416, filed on Sep. 10, 2010, which is adivisional of U.S. patent application Ser. No. 12/100,893, filed on Apr.10, 2008 which issued as U.S. Pat. No. 7,793,515 on Sep. 14, 2010, whichis a divisional of U.S. patent application Ser. No. 11/208,074, filed onAug. 18, 2005, which issued as U.S. Pat. No. 7,363,772 on Apr. 29, 2008,which claims the benefit of U.S. Provisional Application No. 60/602,774,entitled “Refrigerant-Based Energy Storage and Cooling System withSecondary Refrigerant Isolation”, filed Aug. 18, 2004, the entiredisclosure of which is hereby specifically incorporated by reference forall that it discloses and teaches.

BACKGROUND OF THE INVENTION

a. Field of the Invention

The present invention relates generally to systems providing storedthermal energy in the form of ice, and more specifically torefrigerant-based ice storage air conditioning systems used to providecooling load during peak electrical demand.

b. Description of the Background

With the increasing demands on peak demand power consumption, icestorage has been utilized to shift air conditioning power loads tooff-peak times and rates. A need exists not only for load shifting frompeak to off-peak periods, but also for increases in air conditioningunit capacity and efficiency. Current air conditioning units havingenergy storage systems have had limited success due to severaldeficiencies including reliance on water chillers that are practicalonly in large commercial buildings and have difficulty achievinghigh-efficiency. In order to commercialize advantages of thermal energystorage in large and small commercial buildings, thermal energy storagesystems must have minimal manufacturing costs, maintain maximumefficiency under varying operating conditions, emanate simplicity in therefrigerant management design, and maintain flexibility in multiplerefrigeration or air conditioning applications.

Systems for providing thermal stored energy have been previouslycontemplated in U.S. Pat. No. 4,735,064, U.S. Pat. No. 4,916,916, bothissued to Harry Fischer, U.S. Pat. No. 5,647,225 issued to Fischer etal., U.S. patent application Ser. No. 10/967,114 filled Oct. 15, 2004 byNarayanamurthy et al., U.S. patent application Ser. No. 11/112,861filled Apr. 22, 2005 by Narayanamurthy et al., and U.S. patentapplication Ser. No. 11/138,762 filed May 25, 2005 by Narayanamurthy etal. All of these patents utilize ice storage to shift air conditioningloads from peak to off-peak electric rates to provide economicjustification and are hereby incorporated by reference herein for allthey teach and disclose.

SUMMARY OF THE INVENTION

An embodiment of the present invention may therefore comprise a thermalenergy storage and cooling system comprising: a refrigerant loopcomprising: a condensing unit, the condensing unit comprising acompressor and a condenser; an expansion device connected downstream ofthe condensing unit; and, an evaporator on a primary side of anisolating heat exchanger located downstream of the expansion device; acooling loop on a secondary side of the isolating heat exchanger inthermal communication with the primary side of the isolating heatexchanger comprising: a tank filled with a fluid capable of a phasechange between liquid and solid and containing a primary heat exchangertherein, the primary heat exchanger in thermal communication with thesecondary side of the isolating heat exchanger, the cooling loop thatallows transfer of cooling from the secondary side of the isolating heatexchanger to the primary heat exchanger to cool the fluid and to freezeat least a portion of the fluid within the tank in a first time period,the cooling loop that allows transfer of cooling from the primary heatexchanger to the secondary side of the isolating heat exchanger to coolthe primary side of the isolating heat exchanger in a second timeperiod; and, a load heat exchanger in thermal communication with theisolating heat exchanger and the condensing unit that allows coolingcapacity to be transferred from the condensing unit to the load heatexchanger or the primary heat exchanger to the load heat exchanger.

An embodiment of the present invention may further comprise a method ofproviding load cooling with a thermal energy storage and cooling systemcomprising: storing cooling capacity in a first time period comprising:compressing and condensing a refrigerant with a condensing unit in arefrigerant loop; expanding the refrigerant downstream of the condensingunit; and, evaporating the refrigerant on a primary side of an isolatingheat exchanger located downstream of the expansion device; transferringcooling from the expanded refrigerant to a secondary side of theisolating heat exchanger; transferring cooling from the secondary sideof the isolating heat exchanger to a primary heat exchanger located in atank filled with a fluid capable of a phase change between liquid andsolid; and, transferring cooling from the primary heat exchanger to thefluid to freeze at least a portion of the fluid within the tank toprovide stored cooling capacity; utilizing the stored cooling capacityin a second time period comprising: transferring cooling from the fluidto the primary heat exchanger; transferring cooling from the primaryheat exchanger to the isolating heat exchanger; and, transferringcooling from the isolating heat exchanger to a load heat exchanger;providing direct cooling in a third time period comprising: compressingand condensing the refrigerant with the condensing unit in therefrigerant loop; expanding the refrigerant downstream of the condensingunit; and, evaporating the refrigerant downstream of the expansiondevice; and, transferring cooling from the expanded refrigerant to theload heat exchanger.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings,

FIG. 1 illustrates an embodiment of a refrigerant-based thermal energystorage and cooling system with secondary refrigerant isolation.

FIG. 2 is a table representing valve status conditions for therefrigerant-based thermal energy storage and cooling system withsecondary refrigerant isolation illustrated in FIG. 1.

FIG. 3 illustrates a configuration of a refrigerant-based thermal energystorage and cooling system with secondary refrigerant isolation duringan ice-make (charging) cycle.

FIG. 4 illustrates a configuration of a refrigerant-based thermal energystorage and cooling system with secondary refrigerant isolation duringan ice-melt (cooling) cycle.

FIG. 5 illustrates a configuration of a refrigerant-based thermal energystorage and cooling system with secondary refrigerant isolation during adirect cooling (bypass) cycle.

FIG. 6 illustrates another embodiment of a refrigerant-based thermalenergy storage and cooling system with secondary refrigerant isolation.

FIG. 7 illustrates another embodiment of a refrigerant-based thermalenergy storage and cooling system with secondary refrigerant isolation.

FIG. 8 illustrates an embodiment of a net-zero peak powerrefrigerant-based thermal energy storage and cooling system withsecondary refrigerant isolation.

DETAILED DESCRIPTION OF THE INVENTION

While this invention is susceptible to embodiment in many differentforms, there is shown in the drawings and will be described herein indetail specific embodiments thereof with the understanding that thepresent disclosure is to be considered as an exemplification of theprinciples of the invention and is not to be limited to the specificembodiments described.

The disclosed embodiments overcome the disadvantages and limitations ofthe prior art by providing a refrigerant-based thermal storage systemmethod and device wherein a condensing unit and an ice-tank heatexchanger can be isolated through a second heat exchanger. Asillustrated in FIG. 1, an air conditioner unit 102 utilizing acompressor 110 to compress cold, low pressure refrigerant gas to hot,high-pressure gas. Next, a condenser 111 removes much of the heat in thegas and discharges the heat to the atmosphere. The refrigerant comes outof the condenser as a warm, high-pressure liquid refrigerant deliveredthrough a high-pressure liquid supply line 112 to an isolating heatexchanger 162 through an expansion valve 130. This expansion valve 130may be a conventional thermal expansion valve, a mixed-phase regulatorand surge vessel (reservoir) or the like. Low-pressure vapor phase andliquid refrigerant is then returned to compressor 110 via low pressurereturn line 118 completing the primary refrigeration loop.

Cooling is transferred to a secondary refrigeration loop including athermal energy storage unit 106 through the isolating heat exchanger162. The thermal energy storage unit 106 comprises an insulated tank 140that houses the primary heat exchanger 160 surrounded by fluid/icedepending on the current system mode. The primary heat exchanger 160further comprises a lower header assembly 156 connected to an upperheader assembly 154 with a series of freezing and discharge coils 142 tomake a fluid/vapor loop within the insulated tank 140. The upper andlower header assemblies 154 and 156 communicate externally of thethermal energy storage unit 106 with inlet and outlet connections.

An evaporator coil 122 is connected within the secondary closed looprefrigeration circuit to the isolating heat exchanger 162 to transmitcooling from the air conditioner unit 102 to a load in one mode(isolated direct cooling) of the system. The evaporator coil 122 is alsoconnected within the secondary closed loop refrigeration circuit to theprimary heat exchanger 160 to receive cooling in another mode (thermalstorage cooling). Valves 180-186 are placed in various places within thesecondary refrigerant circuits to allow these multi-mode conditions withminimal complexity and plumbing. The valve types and configurationspresented are specified for demonstrative purposes and any variety ofvalve or circuit configurations may be used in conjunction with thedisclosed systems and fall within the scope of the invention. Acting asa collector and phase separator of multi-phase refrigerant, anaccumulator or universal refrigerant management vessel (URMV) 146 is influid communication with both the thermal energy storage unit 106 andthe evaporator coil 122. A liquid refrigerant pump 120 is placed on thedownstream side of the URMV 146 to pump refrigerant through refrigerantloops to either the evaporator coil 122 or the thermal energy storageunit 106 depending upon the current mode.

The embodiment illustrated in FIG. 1 utilizes the air conditioner unit102 as the principal cooling source. The thermal energy storage unit 106operates using an independent refrigerant (or phase change) loop thattransfers the heat between the air conditioner unit 102 and the thermalenergy storage unit 106 or a load, represented by the evaporator coil122. The disclosed embodiment functions in two principal modes ofoperation, ice-make (charging) and ice-melt (cooling) mode.

In ice-make mode, compressed high-pressure refrigerant leaves the airconditioner unit 102 through high-pressure liquid supply line 112 and isfed through an expansion valve 130 to cool the primary side of theisolating heat exchanger 162. Warm liquid and vapor phase refrigerantleaves the isolating heat exchanger 162, returns to the air conditionerunit 102 through the low pressure return line 118 and is fed to thecompressor 110 and re-condensed into liquid. The heat transfer betweenthe primary loop and the secondary loop is accomplished by the isolatingheat exchanger 162. Fluid leaving the isolating heat exchanger 162 onthe secondary side flows to the URMV 146 where the cooled liquid phaserefrigerant is accumulated and stored. The fluid leaves the URMV 146 andis pumped by a liquid refrigerant pump 120 to the thermal energy storageunit 106 where it enters the primary heat exchanger 160 through thelower header assembly 156 and is then distributed through the freezingcoils 142 which act as an evaporator. Cooling is transmitted from thefreezing coils 142 to the surrounding fluid 152 that is confined withinthe insulated tank 140 and eventually produces a block of icesurrounding the freezing coils 142 and storing thermal energy in theprocess. Warm liquid and vapor phase refrigerant leave the freezingcoils 142 through the upper header assembly 154 and exit the thermalenergy storage unit 106 returning to the isolating heat exchanger 162being cooled and condensed once again.

In ice-melt mode, cool liquid refrigerant leaves URMV 146 and is pumpedby a liquid refrigerant pump 120 to the evaporator coil 122 wherecooling is transferred to a load. Warm liquid and vapor phaserefrigerant leave evaporator coil 122 where the liquid phase is returnedto the upper portion of the URMV 146 and vapor phase refrigerant is fedto the upper header assembly 154 of the thermal energy storage unit 106.Vapor phase refrigerant proceeds through the discharge coils 142 drawingcooling from the block of ice 152 surrounding the coils, where warmrefrigerant is cooled and condensed to cool liquid phase refrigerant.This cool liquid phase refrigerant leaves the primary heat exchanger 160via the lower header assembly 156 and exits the thermal energy storageunit 106 where it is fed into the lower portion of the URMV 146. The twoprincipal modes of operation, ice-make and ice-melt performed with theapparatus of FIG. 1 are accomplished with the use of a series of valves180-186 that control the flow of refrigerant through various apparatuswhich can perform dual functions depending upon the mode.

Because the system isolates a primary refrigerant loop 101 from asecondary refrigerant loop 103, the system additionally allows the useof different refrigerants to be used within the device. For example, onetype of highly efficient refrigerant that may have properties that woulddiscourage use within a dwelling (such as propane) may be utilizedwithin the primary refrigerant loop 101, while a more suitablerefrigerant (such as R-22 or R-410A) can be used for the secondaryrefrigerant loop 103 that may enter the dwelling. This allows greaterversatility and efficiency of the system while maintaining safety,environmental and application issues to be addressed.

FIG. 2 is a table representing valve status conditions for therefrigerant-based energy storage and cooling system with secondaryrefrigerant isolation 200 that is illustrated in FIG. 1. As shown in thetable of FIG. 2, during the ice-make process, valve #1 180 is in aclosed condition, valve #2 182 allows flow only from the thermal energystorage unit 106 to the isolating heat exchanger 162, and valve #4 186directs flow from the liquid refrigerant pump 120 to the thermal energystorage unit 106. With the valves in this state, the evaporator coil isremoved from the secondary loop. This causes refrigerant to flow throughthe primary heat exchanger 160, which acts as an evaporator, and returnsrefrigerant through valve #2 to the isolating heat exchanger 162 actingas a condenser. Valve #3 184 allows flow only between the refrigerantpump and the thermal energy storage unit 106. With each of the valves180-186 in this ice-make condition, the system flows as shown in FIG. 3.

During the ice-melt process, valve #4 186 directs flow from the liquidrefrigerant pump 120 to the evaporator coil 122, valve #1 180 is in anopen condition, and valve #2 182 allows flow only from the evaporatorcoil 122 to the thermal energy storage unit 106 and the URMV 146. Withthe valves in this state, the evaporator coil receives cooling totransfer to a load. This causes refrigerant to flow through the primaryheat exchanger 160 in the opposite direction as in the ice-make mode andallows the primary heat exchanger to act as a condenser. Valve #3 184allows flow only between the thermal energy storage unit 106 and theURMV 146. With each of the valves 180-186 in this ice-melt condition,the system flows as shown in FIG. 4.

As described in the above embodiment, the isolating heat exchanger 162acts as an evaporator for the air conditioner unit 102 and as acondenser for the thermal energy storage unit 106. As a result, the airconditioner unit 102 operates at a lower suction temperature, but theloss in efficiency is overpowered by the decrease in cost of the system.During the ice-melt process, there are two options available. Therefrigerant can be fed from the thermal energy storage unit 106 to theevaporator coil 122 as shown in FIG. 1, or the evaporator coil 122 canbe utilized as yet another heat exchanger to exchange heat with yetanother circuit. This option will entail usage of an additional pump todrive the additional circuit.

Additionally shown in the table of FIG. 2 is a condition in which thethermal energy storage capacity of the system may be bypassed and theair conditioner unit 102 is utilized to provide direct cooling to theevaporator coil 122. During the direct cooling process, valve #1 180 isin an open condition, valve #2 182 allows flow from the evaporator coil122 to the isolating heat exchanger 162 and the URMV 146, valve #3 184is closed and valve #4 186 directs flow from the liquid refrigerant pump120 to the evaporator coil 122. With the valves in this state, thethermal energy storage unit is removed from the secondary loop. Thiscauses refrigerant to flow through the isolating heat exchanger 162,which acts as a condenser, and returns refrigerant through the URMV 146to the evaporator coil 122. With each of the valves 180-186 in thisdirect cooling condition, the system flows as shown in FIG. 5.

FIG. 3 illustrates a configuration of the refrigerant-based energystorage and cooling system with secondary refrigerant isolation of FIG.1 during an ice-make (charging) cycle. With each of the valves 180-186in the ice-make mode, as detailed in the table of FIG. 2, compressedhigh-pressure refrigerant leaves the air conditioner unit 102 throughthe high-pressure liquid supply line 112 and is fed through an expansionvalve 130 to cool the primary side of the isolating heat exchanger 162.Warm liquid and vapor phase refrigerant leave the isolating heatexchanger 162 and returns to the air conditioner unit 102 through thelow pressure return line 118 and is fed to the compressor 110 where itis re-condensed into liquid. The heat transfer between the primary loopand the secondary loop is accomplished by the isolating heat exchanger162. Fluid leaving the isolating heat exchanger 162 on the secondaryside flows to the URMV 146 where the cooled liquid phase refrigerant isaccumulated. The fluid leaves the URMV 146 and is pumped by a liquidrefrigerant pump 120 to the thermal energy storage unit 106 where itenters the primary heat exchanger 160 through the lower header assembly156 and is then distributed through the freezing coils 142 which act asan evaporator. Cooling is transmitted from the freezing coils 142 to thesurrounding fluid 152 that is confined within insulated tank 140 andeventually produces a block of ice surrounding the freezing coils 142and storing thermal energy in the process. Cool liquid and vapor phaserefrigerant leave the freezing coils 142 through upper header assembly154 and exit the thermal energy storage unit 106 and return to theisolating heat exchanger 162 and are cooled and condensed once again.

FIG. 4 illustrates a configuration of the refrigerant-based energystorage and cooling system with secondary refrigerant isolation of FIG.1 during an ice-melt (cooling) cycle. With each of the valves 180-186 inthe ice-melt mode, as detailed in the table of FIG. 2, cool liquidrefrigerant leaves URMV 146 and is pumped by a liquid refrigerant pump120 to the evaporator coil 122 where cooling is transferred to a load.Warm liquid and vapor phase refrigerant leave evaporator coil 122 wherethe liquid phase is returned to the upper portion of the URMV 146 andvapor phase refrigerant is fed to the upper header assembly 154 of thethermal energy storage unit 106. Vapor phase refrigerant proceedsthrough the discharge coils 142 drawing cooling from the block of ice152 surrounding the coils where it is cooled and condensed to coolliquid phase refrigerant. This cool liquid phase refrigerant leaves theprimary heat exchanger 160 via the lower header assembly 156 and exitsthe thermal energy storage unit 106 where it is fed into the lowerportion of the URMV 146.

FIG. 5 illustrates a configuration of the refrigerant-based energystorage and cooling system with secondary refrigerant isolation of FIG.1 during a direct cooling cycle. In this configuration the thermalenergy storage unit is bypassed and cooling is delivered directly formthe condenser 111 to the evaporator coil 122 through the isolating heatexchanger 162. With each of the valves 180-186 in the direct coolingmode, as detailed in the table of FIG. 2, the air conditioning unit 102transfers cooling to the primary side of the isolating heat exchanger162 where cooling is transferred to the secondary side to cool andcondense refrigerant in the secondary loop. Cooled liquid refrigerantleaves the isolating heat exchanger 162 and is accumulated in the URMV146. Cool liquid refrigerant leaves URMV 146 and is pumped by a liquidrefrigerant pump 120 to the evaporator coil 122 where cooling istransferred to a load. Warm liquid and vapor phase refrigerant leaveevaporator coil 122 where the liquid phase is returned to the upperportion of the URMV 146 and vapor phase refrigerant is fed back to theisolating heat exchanger 162.

FIG. 6 illustrates another embodiment of a refrigerant-based energystorage and cooling system with secondary refrigerant isolation. Thisembodiment functions without the need for an accumulator vessel or URMVreducing cost and complexity of the system. The embodiment of FIG. 6utilizes the same primary refrigeration loop 101 as shown in FIG. 1using an air conditioner unit 102 with a compressor 110 and condenser111 creating high-pressure liquid refrigerant delivered through ahigh-pressure liquid supply line 112 to an isolating heat exchanger 162through an expansion valve 130 and low-pressure refrigerant then beingreturned to compressor 110 via low pressure return line 118. Cooling istransferred to a secondary refrigeration loop including a thermal energystorage unit 106 through the isolating heat exchanger 162. This thermalenergy storage unit 106 is structurally comparable to that depicted inFIG. 1, and acts as an evaporator in the ice-make mode and as acondenser in the ice-melt mode. An evaporator coil 122 in conjunctionwith an air handler 150 is connected within the secondary closed looprefrigeration circuit to the isolating heat exchanger 162 to transmitcooling from the primary refrigeration loop 101 and provide isolated,direct cooling in one mode.

The evaporator coil 122 is also connected within the closed secondaryloop refrigeration circuit to the thermal energy storage unit 106 toreceive cooling in another mode (thermal storage cooling). Valves182-186 are placed in various places within the secondary refrigerantcircuits to allow these multi-mode conditions with minimal complexityand plumbing. The valve types and configurations presented are specifiedfor demonstrative purposes and any variety of valve or circuitconfigurations may be used in conjunction with the disclosed systems andfall within the scope of the invention. A liquid refrigerant pump 120 inplaced in the secondary refrigeration loop to pump refrigerant to eitherthe evaporator coil 122 or the thermal energy storage unit 106 dependingupon the current mode.

The present embodiment also functions in two principal modes ofoperation, ice-make and ice-melt mode. In ice-make mode, the primaryrefrigerant loop 101 is used to cool the primary side of the isolatingheat exchanger 162 that transfers heat to the secondary loop. Fluidleaving the isolating heat exchanger 162 on the secondary side flows tothe liquid refrigerant pump 120 where the cooled liquid phaserefrigerant is distributed to the thermal energy storage unit 106 actingas an evaporator. The liquid refrigerant pump 120 is placed below thelevel of the isolating heat exchanger 162 so that sufficient liquid headabove the pump can be maintained. Cooling is transmitted to fluid thatis confined within the thermal energy storage unit 106 thus storingthermal energy. Warm liquid and vapor phase refrigerant leaves thethermal energy storage unit 106 and returns to the isolating heatexchanger 162 and is cooled and condensed once again.

In ice-melt mode, cool liquid refrigerant is drawn from the thermalenergy storage unit 106 and is pumped by a liquid refrigerant pump 120to the evaporator coil 122 where cooling is transferred to a load withthe aid of an air handler 150. Warm mixture of liquid and vapor phaserefrigerant leaves the evaporator coil 122 where the mixture is returnedto the thermal energy storage unit 106 now acting as a condenser. Vaporphase refrigerant is cooled and condensed by drawing cooling from thecold fluid or ice. As with the embodiment of FIG. 1, two principal modesof operation, ice-make and ice-melt are performed with the use of aseries of valves 182-186 that control the flow of refrigerant throughvarious apparatus which can perform multiple functions depending uponthe mode.

FIG. 7 illustrates another embodiment of a refrigerant-based energystorage and cooling system. This embodiment deviates from the system ofFIG. 1 by the location of the accumulator vessel and by the addition ofa third mode of operation, a direct cooling mode that bypasses thesecondary refrigeration isolation for use when direct cooling from theair conditioner unit 102 may be desirable. The embodiment of FIG. 6utilizes the same primary refrigeration loop 101 as shown in previousembodiments but additionally adds a direct cooling loop to provide anon-isolated, direct loop to a cooling load from an air conditioner unit102.

As with the previous bi-modal embodiments, the primary refrigerant loop101 can be used to cool the primary side of the isolating heat exchanger162 that transfers heat to the secondary loop. Fluid leaving theisolating heat exchanger 162 on the secondary side flows to the URMV 146and is distributed as liquid refrigerant to either the thermal energystorage unit 106 (ice-make mode), or to the evaporator coil 122 throughthe liquid refrigerant pump 120 (ice-melt mode), and returned to theupper portion of the URMV 146.

In ice-make mode, cooling is transferred directly to the thermal energystorage unit 106 (acting as an evaporator) where the thermal energy isstored as ice. In ice-melt mode, cool liquid refrigerant is drawn fromthe thermal energy storage unit 106 through the URMV 146 and is pumpedto the evaporator coil 122 where cooling is transferred to a load withthe aid of an air handler 150. Warm liquid and vapor phase refrigerantleaves the evaporator coil 122 where the liquid phase is returned to thethermal energy storage unit 106 now acting as a condenser. Vapor phaserefrigerant is accumulated in the upper URMV 146 and drawn into thethermal energy storage unit 106 where it is cooled and condensed withthe cold fluid or ice.

With the current configuration of the energy storage and cooling system,an additional mode can be utilized which has the ability to providenon-isolated, direct cooling from the primary refrigeration loop 101 tothe cooling load through the evaporator coil 122 with the aid of an airhandler 150. In this mode the isolating heat exchanger 162 and thethermal energy storage unit 106 are bypassed to provide this directcooling. As with the previously described embodiments, the principalmodes of operation, ice-make, ice-melt, and direct cooling are performedwith the use of a series of valves 180-189 that control the flow ofrefrigerant through various apparatus.

During the ice-make mode, valve #5 188 and valve #6 189 close theexternal loop to the evaporator coil 122 and retain the fluid within theprimary refrigeration loop 101. Valves #1 180 and #4 186 are closed andvalve #2 182 is open. During the ice-melt process, valve #5 188 andvalve #6 189 remain in the ice-make condition retaining the fluid withinthe primary refrigeration loop 101. Valve #1 180 allows flow only fromthe evaporator coil 122 to the URMV 146 and valve #4 186 allows flowonly from the liquid refrigerant pump 120 to the evaporator coil 122.During the direct cooling mode, valve #5 188 and valve #6 189 preventflow to the isolating heat exchanger 162 and direct flow to the externalloop of the evaporator coil 122. Valve #1 180 allows flow only fromevaporator coil 122 to valve #3 184 that controls a refrigerant receiver190, and flow to the air conditioner unit 102. Valve #4 186 allows flowonly from the air conditioner unit 102 to the evaporator coil 122.

FIG. 8 illustrates an embodiment of a net-zero peak powerrefrigerant-based energy storage and cooling system with secondaryrefrigerant isolation. This embodiment is the system of FIG. 6 with theaddition of a photovoltaic generator 170 placed within the apparatus topower the air handler 150 and the liquid refrigerant pump 120 during theice-melt mode. This allows the system to be used during peak demandtimes at a net-zero power draw from a utility.

Peak usage conditions for air conditioners generally come at times whenthe outside temperature is very high. At such times, it is difficult forthe condenser to reject internal heat to the atmosphere. By utilizingthe aforementioned embodiments, systems that overcome these conditionsare realized. The disclosed systems incorporate multiple operatingmodes, the ability to add optional components, and the integration ofsmart controls that assure energy is stored at maximum efficiency. Whenconnected to a condensing unit, the system stores refrigeration energyin a first time period, and utilizes the stored energy during a secondtime period to provide cooling. In addition, the condensing unit canbypass the refrigerant energy storage system to provide direct orinstantaneous cooling (either isolated or not) during a third timeperiod.

The detailed embodiments detailed above, offer numerous advantages suchas minimizing additional components (and therefore, cost). In addition,the systems use very little energy beyond that used by the condensingunit to store the energy, and with the use of a photovoltaic generator,produces a net-zero power draw system during peak demand power rates.The refrigerant energy storage design has been engineered to provideflexibility so that it is practicable for a variety of applications andhas further advantage over glycol or other single phase systems due topower consumption. This is because the heat load capacity of 1 lb. ofrefrigerant during phase change is 80 times the heat load capacity of 11b. of water. For example, to maintain the same heat load capacity ofwater (with a 10 degree F. temperature change) and refrigerant flowconditions, the power requirement for a refrigerant pump is about1/20^(th) of a water pump. The systems described also eliminate problemswith oil return to the compressor and condensing unit because therefrigerant only traverses the evaporator and the expansion valve afterleaving the condensing unit. The evaporator can be designed for optimumoil drainage, keeping the compressor running smoothly. Finally, byisolating the heat exchanger module during the cooling process, therefrigerant charge can be adjusted optimally for each operatingcondition, ice making and cooling.

The foregoing description of the invention has been presented forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form disclosed, andother modifications and variations may be possible in light of the aboveteachings. The embodiment was chosen and described in order to bestexplain the principles of the invention and its practical application tothereby enable others skilled in the art to best utilize the inventionin various embodiments and various modifications as are suited to theparticular use contemplated. It is intended that the appended claims beconstrued to include other alternative embodiments of the inventionexcept insofar as limited by the prior art.

1. A thermal energy storage and cooling system comprising: a refrigerantloop comprising: a condensing unit, said condensing unit comprising acompressor and a condenser; an expansion device connected downstream ofsaid condensing unit; and, an evaporator on a primary side of anisolating heat exchanger located downstream of said expansion device; acooling loop on a secondary side of said isolating heat exchanger inthermal communication with said primary side of said isolating heatexchanger comprising: a tank filled with a fluid capable of a phasechange between liquid and solid and containing a primary heat exchangertherein, said primary heat exchanger in thermal communication with saidsecondary side of said isolating heat exchanger, said cooling loop thatallows transfer of cooling from said secondary side of said isolatingheat exchanger to said primary heat exchanger to cool said fluid and tofreeze at least a portion of said fluid within said tank in a first timeperiod, said cooling loop that allows transfer of cooling from saidprimary heat exchanger to said secondary side of said isolating heatexchanger to cool said primary side of said isolating heat exchanger ina second time period; and, a load heat exchanger in thermalcommunication with said isolating heat exchanger and said condensingunit that allows cooling capacity to be transferred from said condensingunit to said load heat exchanger or said primary heat exchanger to saidload heat exchanger.
 2. The system of claim 1 wherein said expansiondevice is a thermal expansion valve.
 3. The system of claim 1 whereinsaid refrigerant loop further comprises: a refrigerant receiver foraccumulation and storage of said first refrigerant.
 4. The system ofclaim 1 wherein said expansion device is a mixed-phase regulator.
 5. Thesystem of claim 1 wherein said fluid is a eutectic material.
 6. Thesystem of claim 1 wherein said fluid is water.
 7. The system of claim 1further comprising: an air handler unit that assists in distributingcooling from said load heat exchanger to said heat load; and, aphotovoltaic power source for powering said liquid refrigeration pumpand said air handler.
 8. The system of claim 1 further comprising: avalve structure that facilitates cooling capacity to be transferred fromsaid condensing unit to said primary heat exchanger and prohibitingcooling capacity to be transferred from said condensing unit to saidload heat exchanger.
 9. The system of claim 1 further comprising: avalve structure that facilitates cooling capacity to be transferred fromsaid condensing unit to said load heat exchanger and prohibiting coolingcapacity to be transferred from said condensing unit to said primaryheat exchanger.
 10. The system of claim 1 further comprising: a valvestructure that facilitates cooling capacity to be transferred from saidprimary heat exchanger to said load heat exchanger.
 11. The system ofclaim 1 further comprising: a refrigerant receiver for accumulation andstorage of said first refrigerant.
 12. The system of claim 1 whereinsaid load heat exchanger is at least one mini-split evaporator.
 13. Thesystem of claim 1 wherein said load heat exchanger is a plurality ofevaporators.
 14. A method of providing load cooling with a thermalenergy storage and cooling system comprising: storing cooling capacityin a first time period comprising: compressing and condensing arefrigerant with a condensing unit in a refrigerant loop; expanding saidrefrigerant downstream of said condensing unit; and, evaporating saidrefrigerant on a primary side of an isolating heat exchanger locateddownstream of said expansion device; transferring cooling from saidexpanded refrigerant to a secondary side of said isolating heatexchanger; transferring cooling from said secondary side of saidisolating heat exchanger to a primary heat exchanger located in a tankfilled with a fluid capable of a phase change between liquid and solid;and, transferring cooling from said primary heat exchanger to said fluidto freeze at least a portion of said fluid within said tank to providestored cooling capacity; utilizing said stored cooling capacity in asecond time period comprising: transferring cooling from said fluid tosaid primary heat exchanger; transferring cooling from said primary heatexchanger to said isolating heat exchanger; and, transferring coolingfrom said isolating heat exchanger to a load heat exchanger; providingdirect cooling in a third time period comprising: compressing andcondensing said refrigerant with said condensing unit in saidrefrigerant loop; expanding said refrigerant downstream of saidcondensing unit; and, evaporating said refrigerant downstream of saidexpansion device; and, transferring cooling from said expandedrefrigerant to said load heat exchanger.
 15. The method of claim 14further comprising the step: expanding said refrigerant downstream ofsaid condensing unit with a thermal expansion valve in said first timeperiod or said third time period.
 16. The method of claim 14 furthercomprising the step: accumulating and storing said refrigerant with arefrigerant receiver.
 17. The method of claim 14, wherein said step oftransferring cooling from said expanded refrigerant to said load heatexchanger further comprises: distributing cooling from said load heatexchanger to said heat load with an air handler unit.
 18. The method ofclaim 14, wherein said step of transferring cooling from said expandedrefrigerant to said load heat exchanger further comprises: transferringcooling from said expanded refrigerant to at least one mini-splitevaporator.
 19. The method of claim 14, wherein said step oftransferring cooling from said expanded refrigerant to said load heatexchanger further comprises: transferring cooling from said expandedrefrigerant to a plurality of evaporators.
 20. A means for providingload cooling with a thermal energy storage and cooling systemcomprising: a means for storing cooling capacity in a first time periodcomprising: a means for compressing and condensing a refrigerant with acondensing unit in a refrigerant loop; a means for expanding saidrefrigerant downstream of said condensing unit; and, a means forevaporating said refrigerant on a primary side of an isolating heatexchanger located downstream of said expansion device; a means fortransferring cooling from said expanded refrigerant to a secondary sideof said isolating heat exchanger; a means for transferring cooling fromsaid secondary side of said isolating heat exchanger to a primary heatexchanger located in a tank filled with a fluid capable of a phasechange between liquid and solid; and, a means for transferring coolingfrom said primary heat exchanger to said fluid to freeze at least aportion of said fluid within said tank to provide stored coolingcapacity; a means for utilizing said stored cooling capacity in a secondtime period comprising: a means for transferring cooling from said fluidto said primary heat exchanger; a means for transferring cooling fromsaid primary heat exchanger to said isolating heat exchanger; and, ameans for transferring cooling from said isolating heat exchanger to aload heat exchanger; a means for providing direct cooling in a thirdtime period comprising: a means for compressing and condensing saidrefrigerant with said condensing unit in said refrigerant loop; a meansfor expanding said refrigerant downstream of said condensing unit; and,a means for evaporating said refrigerant downstream of said expansiondevice; and, transferring cooling from said expanded refrigerant to saidload heat exchanger.